The Adobe-created camera profiles are probably slightly different, or you have fluorescent lighting or varying amounts of cloud vs. sun outside, that are coloring one shot differently than the other.

The camera profiles are likely slightly different because Adobe profiles each camera individually and the cameras were announced a year apart so something was done slightly differently from one profiling session to the other. Adobes doesn't just use the same profile when the camera sensors are the same.

The camera manufacturer and Iridient are likely doings something different in their profiling process that makes the cameras the same. It could be due to laziness where they just copied the old profile data and renamed the camera id in it. And Adobe has always had some issues in processing X-Trans data well so maybe they tried harder to get the profile correct in the X-T1 and it affected how the colors look, slightly.

Glass is not perfectly clear so even if the sensor is the same, if the lens is different it could affect the colors, very slightly, and is another reason why not to just use the same profile because the sensor is the same.

I doubt Adobe is going to change their profiles for a slightly difference in comparing cameras that are one year apart in announcement date, because it's not clear that either profile has anything wrong with it.